Isolation of cross-linked polymers



Patented July 26, 1949 who STATES PATENT orFicE is cranes onenessrmxsnrocrnsas *Harolrl "VVittc'ofif, Minneapolis, 1 Mirln., 'assignor toGeneral Mills,Inc.; acorporation of Delaware No llvrawing. jApplicationApril 25, 19 17, Sfiitl N0. 744,038

condensation of polyhydroxy componrids'with pdlyfunctional alk'ylatingagents.

In the copending' application of 'Wittcoif'and Roach, Serial No.705,439, filed'o'ctbberfl, 1946,

entitled Polyhydric alcohols, there is disclosed the preparation of"highly functional polyhydric alcohols by condensing polyhydroxycompounds "with polyfunctional alkylzi ting agents. The alcohols whicharef-produced proba-kily possesscrosslinkageswhich result from thecross-condensations. In order for this high degree of condensation tooc'cur'git is necessary that the tctal-numbier-of groups enterin intothe alkylationreaction be-at least 5. 'Thus'thealcoholmay contain 3hydroxyl groups, as for example, glycerimand the'alkylatingagentmaycontain 2 alkylating groups as in the case of glycerol dichlorohydrin.It is also possible'torelyon'thehydroxyl group "of the glyceroldichlorchydrinas 'oneofthe groups entering the alkylation reaction.Under these conditions, highly functional polyhydric alcohols areobtained which protamy contain" cross-linkages. -'-'-It has been foundth'at' these cross l-inlied alcohols'niake excellent drying oils,alkydresins, allylethe'rs, rosin acidesters, and'the like. *Hdwever, asthese polyhydric alcohols are produced in accordance with the disclosureof the above referred to application, they contain, in addition to thehighly condensed alcohols, a certain amount of the original polyhydroxycompound, as well as some relatively low molecular weight linear etheralcohols which result from this condensation.

For the production of the best drying oils, alkyd res-ins, ester gums,and the like, it is desirable that the highly condensed alcohols be asfree as possible from the original reactants and from the low molecularweight ether alcohols. The usual methods of separation, however, are notfeasible. For example, distillation is unsatisfactory, for although somemonomeric material such as glycerol may be distilled off, the lowmolecular weight ether alcohols are too high-boiling to be distilled,and cannot be separated from the highly condensed alcohols. Similarly,derivatives such as the acetates or the allyl ethers are notdistillable.

It was found, however, that it is possible to convert the originalpolyhydroxy compound and the low molecular weight ether alcohols toaceals without so converting the highly condensed alcohols. For somereason or other, the highly condensed alcohols do not form acetals. The

. ,2 acetals are "soluble in ac'etone, whereas' the hiehly condensedalcohols are insoluble, and inithis holsand the linear e th'er alcoholsas a a :mixture i rom thehighly condensed alcohols.

In' -generaI the f1 invention is' carried 'out by treating the reactionmixture resulting fro'ni the condensation oi the polyhy'clroxy'comp'oundand pclyrunctional alkyl'ating agent, 1 with-' methanol 1 andh'ydro'chioric-"a'cid to' neutralize the alkaline catalyst. "Thereaftertnemixture 'is' evaporated to dryness and the rganic materiaL may -b eextractedwith a' suitable 'solveht; such as rrie thanol. Thissolution-is then" se arated TEOIIY-th re'sidual inorganic materialandthealcohol evaporated to le'a'ive a viscous'syr'u'p. Thi's viscous-syrup-is then I converted to 'an a'cetal in the' conventionar'manher,as for example by t'reatin'g it with acidified :a'cetenepsucn as amixture of" acetone" and :anhydrous hydrogen chlor ide. -Thereaction-pro- 'ceeds readily and two phases areobtained. "The upperpnase corisisting-ofacetone and'ac'etals rnay be decanted-,- leaving''the highly condensed polyhydric alcoholsbehind. T The acetals may, of

course-be converted to thealcohols readily loy conventi'onal procedures.

The following example -Wl11 serve to illustr aite tneinventien ExampleGlycerol 485 parts) and aqueous sodium hydroxide (34.9%, 1260 parts)were heated to 90 C. and glycerol dichlorohydrin (645 parts) was addedwith stirring over a period of five hours. The reaction was allowed tocontinue for two hours more, after which it was cooled, diluted withmethanol and neutralized with hydrochloric acid. The mixture wasfiltered and the filtrate evaporated to yield a mixture of salt andproduct from which the latter was extracted with methanol. After theremoval of methanol, there resulted a syrup from which most of theexcess glycerol was removed by distillation. This, however, is notnecessary since it can be removed readily later as the acetonederivative. The final product had a hydroxyl content of 27.3%.

This condensation product (200 parts) was mixed with acetone (1000parts) which contained 19 parts of anhydrous hydrogen chloride, Themixture was shaken and cooled externally. Thereafter, sodium sulfateparts) was added and the mixture was stirred overnight. This long periodof reaction, however, is not necessary, and ordinarily a few hours aresuflicient.

The acetone was decanted. It contained the isopropylidene derivatives ofsome glycerol which was not previously removed and of polyglycerolsabove diglycerol. This was not the desired product. However, it wasrecovered by neutralizing the solution with alcoholic caustic andremoving the acetone. The residue (142 parts) could be hydrolyzed toobtain the free hydroxy compounds.

The desired product which was the highly condensed polyether alcohol wasobtained from the residue remainin after the decantation of the acetone.This residue was treated with methanol, heated slightly and filtered.Evaporation of the filtrate yielded 86 parts of product with a hydroxylcontent of 21.6%.

In order to determine the molecular weight, this product was convertedto the acetate. The molecular weight of the acetate, determined by therise of boiling point of carbon tetrachloride and of ethylene dibromide,was 1256.6. Thus the molecular weight of the free hydroxy compound was819.

While various modifications of the above invention have been described,it is to be understood that the same is not limited thereto, but may bevaried within the scope of the following claims.

I claim as my invention:

1. Process of separating highly condensed cross-linked polyetheralcohols from a mixture resulting from the alkaline condensation ofglycerol and glycerol dichlorohydrin, said mixture containing highlycondensed cross-linked polyether alcohols, glycerol and linear polyetheralcohols which comprises vaporizing residual glycerol, treating theresidue with acidified acetone to convert alcohols other than the highlycondensed polyether alcohols to acetals, and separating the acetals fromthe highly condensed cross-linked polyether alcohols.

2. Process of separating highly condensed cross-linked polyetheralcohols from a mixture resulting from the alkaline condensation ofglycerol and glycerol dichlorohydrin, said mixture containing highlycondensed cross-linked polyether alcohols, glycerol and linear polyetheralcohols which comprises treatin the mixture with an acidified lowaliphatic carbonyl-containing compound to convert alcohols other thanthe highly condensed polyether alcohols to acetals to form two phases,one containing the carbonyl-containing compound and the acetals, theother containing the highly condensed cross-linked polyether alcohols,and separating the one phase from the other.

3. Process of separating highly condensed cross-linked polyetheralcohols from a mixture resulting from the alkaline condensation ofglycerol and glycerol dichlorohydrin, said mixture containing highlycondensed cross-linked polyether alcohols, glycerol and linear polyetheralcohols which comprises treating the mixture with acidified acetoneunder anhydrous conditions to convert alcohols other than the highlycondensed polyether alcohols to acetals and to form two phases, onecontaining acetone and the acetals, the other containing the highlycondensed cross-linked polyether alcohols, and separating the twophases.

4. Process of separating highly condensed cross-linked polyetheralcohols from an aqueous reaction mixture resulting from the alkalinecondensation of glycerol and glycerol dichlorohydrin, said mixturecontaining highly condensed cross-linked polyether alcohols, glyceroland linear polyether alcohols which comprises removing water from thereaction mixture to leave a residue, extracting the residue withmethanol, evaporating the methanol, treating the remainder with acetoneacidified with anhydrous hydrogen chloride, to convert alcohols otherthan the highly condensed polyether alcohols to acetals and to form twophases, one containing the acetone and the acetals, the other containingthe highly condensed cross-linked polyether alcohols, and separating thetwo phases.

HAROLD WI'IZTCOFF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,922,459 Schmidt Aug. 15, 19332,223,421 Hubacher Dec. 3, 1940

